1. Field of the Invention
The embodiments disclosed herein relate to an image processing apparatus and an image processing method.
2. Description of the Related Art
For the purpose of early diagnosis of lifestyle diseases or diseases that rank high as a cause of blindness, the inspection of the fundus oculi of the human eye has been widely used. A scanning laser ophthalmoscope (SLO), which is an ophthalmological instrument that utilizes the principle of confocal laser scanning microscopy, is a device that uses laser light, which serves as measurement light, to raster-scan the fundus oculi to quickly obtain a high-resolution two-dimensional image from the intensity of the return light of the laser light. In recent years, adaptive optics SLOs (AO-SLOs) including an AO system configured to measure the aberrations of the eye being examined in real time by using a wavefront sensor and to correct the aberration of the measurement light that occurs in the eye being examined or the aberration of the return light of the measurement light by using a wavefront correction device have been developed. The AO-SLOs facilitate the acquisition of high-lateral-resolution two-dimensional images (hereinafter sometimes referred to as “AO-SLO images”). In addition, the photoreceptor cells in the retina are extracted from obtained two-dimensional retinal images, and the density or distribution of the photoreceptor cells is analyzed to attempt the diagnosis of a disease or the evaluation of drug response.
Image processing for detecting the photoreceptor cells may be performed with high accuracy by utilizing medical knowledge of photoreceptor cells. For example, it is known that the density of photoreceptor cells decreases as the distance from the macula lutea increases. In order to take advantage of this knowledge, users need to know the distance from the macula lutea to the region being analyzed.
Due to the smaller view angle of AO-SLO images than SLO images, an AO-SLO image, which is obtained by imaging the region in which the density is to be evaluated, does not generally include the macula lutea. Thus, it is difficult to know the exact distance from the macula lutea to the region. Accurate evaluation of the photoreceptor cells is therefore difficult to achieve.